This is an interesting thread, as I too, was on the fence for some time. We finally went ahead and had both dogs chipped (I've read too many stories about dogs stolen/lost etc...and like the idea of having a permanent way of identifying that the dog is mine) I found this site.
Healthypet.com Now it is obviously pro microchipping, but it addressses a lot of questions. Personally, I think that at this time there is no right or wrong. If you are comfortable with it, go for it. If not, don't.